EP0240055A1 - Anordnung zur Kompensation einer nichtlinearen Verzerrung eines zu digitalisierenden Eingangssignals und Echokompensator mit einer derartigen Anordnung - Google Patents

Anordnung zur Kompensation einer nichtlinearen Verzerrung eines zu digitalisierenden Eingangssignals und Echokompensator mit einer derartigen Anordnung Download PDF

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Publication number
EP0240055A1
EP0240055A1 EP87200454A EP87200454A EP0240055A1 EP 0240055 A1 EP0240055 A1 EP 0240055A1 EP 87200454 A EP87200454 A EP 87200454A EP 87200454 A EP87200454 A EP 87200454A EP 0240055 A1 EP0240055 A1 EP 0240055A1
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EP
European Patent Office
Prior art keywords
signal
correction value
arrangement
input signal
analogue
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP87200454A
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English (en)
French (fr)
Other versions
EP0240055B1 (de
Inventor
Simon Johannes Maria Tol
Kornelis Jan Wouda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Network Systems International BV
Original Assignee
AT& T NETWORK SYSTEMS NEDERLAND BV
AT&T and Philips Telecommunications BV
AT&T Network Systems International BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by AT& T NETWORK SYSTEMS NEDERLAND BV, AT&T and Philips Telecommunications BV, AT&T Network Systems International BV filed Critical AT& T NETWORK SYSTEMS NEDERLAND BV
Publication of EP0240055A1 publication Critical patent/EP0240055A1/de
Application granted granted Critical
Publication of EP0240055B1 publication Critical patent/EP0240055B1/de
Expired legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H04B3/23—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/20—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other
    • H04B3/23—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers
    • H04B3/238—Reducing echo effects or singing; Opening or closing transmitting path; Conditioning for transmission in one direction or the other using a replica of transmitted signal in the time domain, e.g. echo cancellers using initial training sequence

Definitions

  • the invention relates to an arrangement for compensating for non-linear distortion in an input signal to be digitized, comprising an analogue-to-digital converter for converting the input signal into an amplitude-time discrete output signal and to an echo cancelling system comprising such an arrangement.
  • the non-linear transmission in the different stages of the analogue transmission circuit and also the non-linearity of the analogue-to-digital converter may prevent a linear conversion of the applied analogue signal into a digital signal.
  • the invention has for its object to provide a solution of the above-mentioned problem, which is practically feasible and in which a very good linearity can be obtained at, in addition, comparatively low cost.
  • the invention provides an arrangement of the above-mentioned type, wherein there are provided means for deriving a set of coefficients associated with an orthogonal signal representation of a signal which is related to the input signal, a memory in which a Table of correction values can be stored, means for addressing the memory for reading a correction value from the Table, each coefficient determining an address for the memory, means for summing the correction values read and the output signal of the analogue-to-digital converter for providing a linearized signal, and an adaptive control loop having means for determining a linear approximation of the input signal, means arranged for determining the difference between the linearized signal and the signal which is a representation of the linear approximation of the input signal, means for determining a new correction value from this difference and the correction value read and means for substituting in the Table the new correction value for the correction value read.
  • the invention more specifically relates to an echo cancelling system comprising an arrangement according to the invention.
  • an echo canceller On digital transmission in two directions via a two-wire link the use of an echo canceller is imperative, since the signal at the input of a receiver for such a two-wire link contains a strong echo component in response to the own transmit signal of the transmitter associated with the receiver.
  • the echo signal By now reducing the received signal by a signal which is the best possible approximation of the fraction of the signal transmitted by its own transmitter, the what is commonly referred to as the echo signal, present in the received signal, it is possible to derive the actually received signal from the received signal, inspite of the strong echo component contained therein.
  • a filter which is capable of compensating for any linear combination of transmitted preceding symbols a what is commonly referred to as a transversal filter.
  • This manner of echo cancellation is extensively described in N.A.M. Verhoeckx et al : "Digital echo cancellation for baseband data transmission" I.E.E.E. Transactions ASSP, Volume ASSP-27, No. 6, December 1979, pages 768-781.
  • a non-linear tranmission characteristic in the signal path between the transmitter and the receiver can however not be compensated for by the tranversal filter and produces residual errors of such a value that an adequate echo cancellation is not possible.
  • the echo cancelling system according to the invention also provides a solution for this problem, in that an arrangement according to the invention is provided, by means of which the non-linearity in the digitM1 system subjected to echo cancellation is already effectively compensated for prior to this echo cancellation, so that the actual echo cancellation is performed on the signal without non-linear distortion, it then being possible to use advantageously a transversal filter comprising an adaptive control loop for this echo cancellation.
  • said Patent Specification relates to an echo canceller in which an analogue signal is supplied and in which also here an analogue echo cancellation signal is used, so that an A/D converter and an D/A converter are required with the errors and costs inherent thereto.
  • An analogue signal whose origin is not important, at least for the time being, for the description of the invention, is applied to the input terminal denoted by reference numeral 1 in Figure 1.
  • the analogue signal at terminal 1 does not yet have a non-linear distortion component, these components will be introduced without fail in the A/D converter 2 to which the signal is applied.
  • the amplitude and time-discrete output signal of the A/D converter has non-linear distortion relative to the signal which should be present in the ideal case, that is to say without non-linear distortion.
  • a set of coefficients which are associated with an orthogonal signal representation of a signal related to the analogue signal at terminal 1 is derived from the output signal of the A/D converter 2 according to the invention.
  • the signal related to the analogue signal at terminal 1 is the output signal of the A/D converter and this signal is applied to a quantization circuit 3 with the object of deriving the set of coefficients.
  • quantization circuit 3 the signal is distributed in a customary manner into a plurality of segments, consecutive segments representing consecutive amplitude value ranges and each segment constituting in an unambiguous manner an address for a Table stored in a memory 4, for example a RAM.
  • This Table contains a compensation value for each segment.
  • the address compensation value is applied to an adder circuit 5 which adds together the output signal of the A/D converter 2 and the compensation signal.
  • the signal supplied from the output of the adder circuit 5 thus has considerably less non-linear distortion than the output signal of the A/D converter.
  • the characteristic h can, for example, be represented by means of any set of coefficients associated with an orthogonal signal representation of a signal related to the input signal, having its own correction value in the Table for each coefficient.
  • circuit shown in Figure 1a includes an adaptive control loop, which is generally denoted by reference numeral 20, comprising a multiplier 7, subtracting circuits 8 and 18 and a circuit which generally is denoted by reference numeral 16.
  • Circuit 16 comprises a detector 21, a transversal filter 22 whose coefficients can be adaptively readjusted, and a subtracting circuit 23.
  • the detector 21 receives the output signal from subtracting circuit 5 and from the output terminal 16" of the circuit 16 supplies the symbols detected in the output signal of circuit 5.
  • the output signal of detector 21 is also coupled to an input of the transversal filter 22, whose output produces at the output terminal 16' of circuit 16 a signal which is a linear estimation of the output signal of circuit 5, which estimation is effected with the aid of the symbols detected by the detector 21, and on the basis of the coefficients of the transversal filter 22.
  • an adaptive rontrol loop including the subtracting circuit 23 is provided for adaptively readjusting the coefficients of the transversal filter 22.
  • This subtracting circuit determines the difference between the output signal of circuit 5 and the transversal filter output signal and produces at its output a correction signal for correcting the coefficients of the transversal filter 22, which correction signal is applied to a second input terminal of filter 22.
  • Subtracting circuit 18 determines the difference between the signal supplied by adder circuit 5 and the output signal of circuit 16 at terminal 16'.
  • the output signal of subtracting circuit 18 is coupled to the multiplier 7, in which the signal is multiplied by a previously determined control constant k .
  • the actually used Table value is reduced by the deviation determined by multiplier 7 via the control loop 20 and this new Table value is entered into the memory 4 to replace the old Table value.
  • the analogue signal applied to terminal 1 must satisfy one specific condition : it must consists of a linear combination of sound signals, which combination must be derivable from either the signal itself, or from an other source. If this condition is not satisfied, it is not possible to determine at the output of the A/D converter whether non-linear distortion of the input signal has occurred or not occurred.
  • a signal satisfying said condition is, for example, an analogue signal present at the input of the receiver of a digital transmission signal.
  • the signal can be formed from a digital three-level transmit signal which, because of distortion and transmission line properties can be distorted such on reception that it might be considered as an analogue signal. From this signal it is however indeed always known that it must result from a signal having only three levels.
  • Figure 2 shows an echo cancellation system according to the invention.
  • the system shown in Figure 2 comprises a transmitter 10, a receiver 11 and a hybrid circuit 12,via which digital transmission through a two-wire line 13 can be effected. Because of the non-ideal properties of the hybrid circuit 12 and the comparatively high cable attenuation on line 13, the signal received on line 14 will comprise a significant echo component of its own transmitter 10 and only a comparatively weak signal received from a different transmitter 10', not shown.
  • an echo canceller 15 has been provided in known manner.
  • This echo canceller 15 is of a known type and preferably includes a transversal filter, so that a linear estimation of the echo component is available at the output of echo canceller 15.
  • the signal at the output terminal 16' of circuit 16 which is a linear estimation of the overal received signal, is added in summing circuit 17 to the output signal of echo canceller 15, so that the output signal of summing circuit 17, which is coupled to a subtracting circuit 18, is the sum of the linear estimation of the total overall received signal and the linear estimation of the echo component and, consequently, a linear estimation of the signal on line 14.
  • the output signal of summing circuit 5 which is the output signal of the A/D converter 2 corrected by the Table values and used for compensating non-linear distortion, is reduced by the linear estimation of the total received signal inclusive of the echo signal, so that at the output terminal of circuit 18 a signal is present which is suitable for readjusting the values in memory 4, in the manner as described with reference to Figure 1a.
  • the subtracting circuit 19 has one end coupled to the entire received signal inclusive of the echo signal, in which signal the non-linear distortion has been compensated for in accordance with the invention by means of the arrangement shown in Figure 1a, and its other side to the linear estimation of the echo signal, determined by circuit 15.
  • the output of circuit 19 supplies a signal which is suitable for making a linear estimation, in circuit 16, of the actually received signal and for detecting the received symbols, which detection actually is the ultimate object of the system.
  • the detected, received symbols are supplied from an output terminal 16" of circuit 16 and are applied to the receiver 11.
  • the amplitude of the signal at the output of the A/D converter 2, and consequently its degree of excitation is predominantly determined by the echo signal
  • the echo signal is formed, for example, by 16 bits, it is, for example, possible to utilize the four most significant bits 15-12 as an address for memory 4.
  • each Table value After each Table value has been corrected once, the correction can be stopped for a predetermined period of time and be resumed thereafter in the same way, or alternatively the first value in the Table can directly be corrected.
  • This procedure assumes that each Table value is corrected cyclically.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Filters That Use Time-Delay Elements (AREA)
  • Compression, Expansion, Code Conversion, And Decoders (AREA)
EP19870200454 1986-03-28 1987-03-11 Anordnung zur Kompensation einer nichtlinearen Verzerrung eines zu digitalisierenden Eingangssignals und Echokompensator mit einer derartigen Anordnung Expired EP0240055B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8600815 1986-03-28
NL8600815A NL8600815A (nl) 1986-03-28 1986-03-28 Inrichting voor het kompenseren van niet-lineaire vervorming in een te digitaliseren ingangssignaal en een echokompensatiestelsel voorzien van een dergelijke inrichting.

Publications (2)

Publication Number Publication Date
EP0240055A1 true EP0240055A1 (de) 1987-10-07
EP0240055B1 EP0240055B1 (de) 1991-11-06

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19870200454 Expired EP0240055B1 (de) 1986-03-28 1987-03-11 Anordnung zur Kompensation einer nichtlinearen Verzerrung eines zu digitalisierenden Eingangssignals und Echokompensator mit einer derartigen Anordnung

Country Status (7)

Country Link
US (1) US4746902A (de)
EP (1) EP0240055B1 (de)
JP (1) JP2515784B2 (de)
AU (1) AU587156B2 (de)
CA (1) CA1266104A (de)
DE (1) DE3774311D1 (de)
NL (1) NL8600815A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0280898A1 (de) * 1987-02-18 1988-09-07 Siemens Aktiengesellschaft Schaltungsanordnung zum Unterdrücken von Echosignalen
WO1990013185A1 (en) * 1989-04-27 1990-11-01 Telefonaktiebolaget Lm Ericsson A method and arrangement for avoiding erroneous echo-elimination and/or equalization in a telecommunication system
AU630771B2 (en) * 1989-12-05 1992-11-05 Rhone-Poulenc Sante Process for preparing synergistins
WO1998042082A3 (en) * 1997-03-17 1998-12-03 Nokia Telecommunications Oy Method and arrangement for forming an address
US7245244B1 (en) * 2004-08-03 2007-07-17 Analog Devices, Inc. Correction methods and structures for analog-to-digital converter transfer functions

Families Citing this family (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8600815A (nl) 1986-03-28 1987-10-16 At & T & Philips Telecomm Inrichting voor het kompenseren van niet-lineaire vervorming in een te digitaliseren ingangssignaal en een echokompensatiestelsel voorzien van een dergelijke inrichting.
US4862168A (en) * 1987-03-19 1989-08-29 Beard Terry D Audio digital/analog encoding and decoding
JPH01254024A (ja) * 1988-04-02 1989-10-11 Hitachi Ltd Ａ／ｄ変換器
US4975700A (en) * 1989-05-24 1990-12-04 Texas Instruments, Incorporated Analog-to-digital converter with non-linear error correction
US4999830A (en) * 1989-09-25 1991-03-12 At&T Bell Laboratories Communication system analog-to-digital converter using echo information to improve resolution
US4999627A (en) * 1989-09-25 1991-03-12 At&T Bell Laboratories Analog-to-digital converter using prescribed signal components to improve resolution
US4996530A (en) * 1989-11-27 1991-02-26 Hewlett-Packard Company Statistically based continuous autocalibration method and apparatus
JP3011424B2 (ja) * 1990-01-24 2000-02-21 株式会社東芝 Ａ／ｄ変換器
US4985702A (en) * 1990-04-02 1991-01-15 Triquint Semiconductor, Inc. Analog to digital converter with second order error correction
JP3158414B2 (ja) * 1990-06-25 2001-04-23 日本電気株式会社 エコーキャンセラ
US5281968A (en) * 1991-09-06 1994-01-25 Nec Corporation DC offset correction circuit for A/D converter
US5623513A (en) * 1993-12-13 1997-04-22 Amati Communications Corporation Mitigating clipping and quantization effects in digital transmission systems
US5594612A (en) * 1994-08-24 1997-01-14 Crystal Semiconductor Corporation Analog-to-digital converter with digital linearity correction
US5583501A (en) * 1994-08-24 1996-12-10 Crystal Semiconductor Corporation Digital-to-analog converter with digital linearity correction
US5594439A (en) * 1994-08-24 1997-01-14 Crystal Semiconductor Corporation Diagnosing problems in an electrical system by monitoring changes in nonlinear characteristics
KR100219155B1 (ko) * 1996-09-11 1999-09-01 윤종용 디지탈/아날로그 변환장치
US6198416B1 (en) 1999-04-16 2001-03-06 Scott R. Velazquez Linearity error compensator
US6813311B1 (en) 2000-03-14 2004-11-02 Globespan Virata Corporation Non-linear echo cancellation for wireless modems and the like
EP1137232B1 (de) * 2000-03-23 2006-11-29 Matsushita Electric Industrial Co., Ltd. Digitaler Empfänger
JP2001339449A (ja) * 2000-03-23 2001-12-07 Matsushita Electric Ind Co Ltd ディジタル受信装置
US7324598B2 (en) * 2002-07-15 2008-01-29 Intel Corporation Apparatus and method to reduce quantization error
DE10305972A1 (de) * 2003-02-13 2004-09-02 Micronas Gmbh Kompensationsschaltungsanordnung und Kompensationsverfahren zum Kompensieren von nicht-linearen Verzerrungen eines AD-Wandlers
US6856191B2 (en) * 2003-02-21 2005-02-15 Optichron, Inc. Nonlinear filter
DE10332008B4 (de) * 2003-07-14 2006-08-10 Infineon Technologies Ag Elektrische Schaltung sowie Verfahren zum Testen von elektronischen Bauteilen
US7106533B2 (en) * 2004-10-15 2006-09-12 International Business Machines Corporation Apparatus, system, and method for mitigating signal asymmetry
CN101796732B (zh) * 2007-10-12 2013-08-14 富士通株式会社 接收电路及其ad转换器的转换表生成方法以及信号传输系统

Citations (3)

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Publication number Priority date Publication date Assignee Title
FR2381283A1 (fr) * 1977-02-16 1978-09-15 Aga Ab Appareil de mesure de longueurs lineaires ou angulaires
US4237463A (en) * 1977-10-24 1980-12-02 A/S Elektrisk Bureau Directional coupler
DE3430187A1 (de) * 1983-09-23 1985-04-11 Siemens-Albis AG, Zürich Elektronische gabelanordnung

Family Cites Families (4)

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JPS6046899B2 (ja) * 1980-09-26 1985-10-18 日本電気株式会社 反響消去装置
GB8511835D0 (en) * 1985-05-10 1985-06-19 British Telecomm Adaptive digital filter
US4612533A (en) * 1985-06-12 1986-09-16 The United States Of America As Represented By The Secretary Of The Air Force Harmonic distortion reduction technique for data acquistion
NL8600815A (nl) 1986-03-28 1987-10-16 At & T & Philips Telecomm Inrichting voor het kompenseren van niet-lineaire vervorming in een te digitaliseren ingangssignaal en een echokompensatiestelsel voorzien van een dergelijke inrichting.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2381283A1 (fr) * 1977-02-16 1978-09-15 Aga Ab Appareil de mesure de longueurs lineaires ou angulaires
US4237463A (en) * 1977-10-24 1980-12-02 A/S Elektrisk Bureau Directional coupler
DE3430187A1 (de) * 1983-09-23 1985-04-11 Siemens-Albis AG, Zürich Elektronische gabelanordnung

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0280898A1 (de) * 1987-02-18 1988-09-07 Siemens Aktiengesellschaft Schaltungsanordnung zum Unterdrücken von Echosignalen
WO1990013185A1 (en) * 1989-04-27 1990-11-01 Telefonaktiebolaget Lm Ericsson A method and arrangement for avoiding erroneous echo-elimination and/or equalization in a telecommunication system
EP0399968A1 (de) * 1989-04-27 1990-11-28 Telefonaktiebolaget L M Ericsson Verfahren und Vorrichtung zum Vermeiden falscher Echoelimination und/oder zum Vermeiden falscher Entzerrung in einem Telekommunikationssystem
AU622799B2 (en) * 1989-04-27 1992-04-16 Telefonaktiebolaget Lm Ericsson (Publ) A method and arrangement for avoiding erroneous echo-elimination and/or equalization in a telecommunication system
US5189637A (en) * 1989-04-27 1993-02-23 Telefonaktiebolaget L M Ericsson Method and apparatus for preventing erroneous echoelimination and equalization
AU630771B2 (en) * 1989-12-05 1992-11-05 Rhone-Poulenc Sante Process for preparing synergistins
WO1998042082A3 (en) * 1997-03-17 1998-12-03 Nokia Telecommunications Oy Method and arrangement for forming an address
AU741822B2 (en) * 1997-03-17 2001-12-13 Nokia Telecommunications Oy Method and arrangement for forming an address
US6799021B1 (en) 1997-03-17 2004-09-28 Nokia Telecommunications Oy Method and arrangement for forming an address
US7245244B1 (en) * 2004-08-03 2007-07-17 Analog Devices, Inc. Correction methods and structures for analog-to-digital converter transfer functions

Also Published As

Publication number Publication date
AU7072687A (en) 1987-10-01
AU587156B2 (en) 1989-08-03
NL8600815A (nl) 1987-10-16
US4746902A (en) 1988-05-24
CA1266104A (en) 1990-02-20
EP0240055B1 (de) 1991-11-06
JPS62294337A (ja) 1987-12-21
JP2515784B2 (ja) 1996-07-10
DE3774311D1 (de) 1991-12-12

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